Recently, an apparatus for mobile communication, especially a cellular phone has rapidly come into wide use, and most of areas with a certain population are covered. However, there are some areas where radio waves from a general existing base station (i.e., wide-area base station) cannot reach, which makes the area out of service, and where the radio waves is weak, which brings a communication into unstable, such as the interior space of a house or a building, or a place in an unfavorable situation. A small base station having low output power and providing a cell (service area) with a radius of from several meters to several tens of meters has been developed to cover such areas out of service (see http://www.nttdocomo.co.jp/info/news_release/page/070710—01.html). This small-scale cell itself, or a small base station providing the cell is called as a femtocell. Though the femtocell is very small, it is in the range of a base station, so that the femtocell is not placed on the market in Japan because there are restrictions of various related regulations about notification of installation place, permission, operation time and the like.
On the other hand, since an always-on connection of a broadband line such as an optical line, ADSL or the like has been spread in the usual home, an infrastructure (i.e., backbone) for connecting the femtocell to a mobile communication system is being developed. Moreover, there is also a merit that a telecommunication provider can provide communication service without using a bandwidth of the general existing base station which is supposed to be used by utilizing the femtocell and the broadband line. Accordingly, it is expected that the femtocell will be developed and used on a full scale in the near future by restrictions of related regulations being relaxed or the applications being changed.